I use gmail, and its a fairly old account so its probably floating around the internet from more innocent days.
I've noticed a good chunk of spam I have that's local to me is sent via the same service. I presume they got it somewhere, and its not one of my +suffix emails. Rather than unsubscribing to each vendor, I'd like to completely block mails sent via this service
Here's an example of one, sent by an insurance company. The domain its sent by seems to belong to an email marketing company - and as such is of no interest to me. I don't want any mails sent via their servers. I don't want to block admin@sgassure.com specifically or @sgassure.com. I know how to do that. I want to block the service they are using.
Is there any way to filter out emails sent via sendersrv.com or any specific relaying domain in gmail?